The prospect of providing wireless implantable devices for the purpose of medical treatment, rehabilitation, monitoring and/or diagnostics is an attractive one, whereby locally targeted devices can provide significant benefits over externally implemented alternatives. However, while implantation in itself can pose a series of challenges, whether in the process of implanting the device or in providing manufacturing materials that will not adversely affect the condition of the subject, other challenges are also imminent. Namely, most implantable devices will be battery powered and therefor, if the device is to have a sufficiently long lifespan, highly efficient circuitry or adequate battery recharging applications can become particularly relevant. Furthermore, communication of information to and from the implanted device may be of particular importance depending on the application at hand, while traditional communication techniques and components may not be readily amenable to implantation, or appropriate in such contexts. Namely, while a number of examples are available for the provision of wireless data communications, for example as provided by Sharma et al. in U.S. Pat. No. 5,615,229 to a Short Range Inductively Coupled Communication System Employing Time Variant Modulation, these and other such examples do not contemplate the limitations and constraints applied to implantable devices, nor do they contemplate the particular conditions in which implantable devices are designed to operate, and media through which signals communicated thereby or thereto are subjected to.
Also, as will be appreciated by the person of ordinary skill in the art, communicating data from an external device to an implanted device, for example as described in U.S. Pat. No. 6,671,559 to Goldsmith et al. for a Transcanal, Transtympanic Cochlear Implant System for the Rehabilitation of Deafness and Tinnitus, wherein acoustic data is communicated via magnetic inductive coupling to the implanted device for the purpose of stimulating the inner ear, does not generally pose as significant challenges with respect to power consumption efficiency. Namely, the internal reception of externally transmitted data can generally be much more straightforward in implementation than the reverse. It will be appreciated that other challenges and limitations associated with implanted device communications may be of particular relevance depending on the application at hand, and that while power consumption and conservation may be highlighted to some extent herein, other aspects of implantable device communications may also be considered pertinent in the present discussion.
In other examples, an implanted battery-operated device can be inductively recharged via an external device. For example, energy can be transferred transcutaneously via magnetic induction between an external charger and implanted device, such as described in U.S. Pat. No. 5,713,939 to Nedugadi et al. for a Data Communication System for Control of Transcutaneous Energy Transmission to an Implantable Medical Device and U.S. Pat. No. 6,772,011 to Dolgin for Transmission of Information from an Implanted Medical Device. In these examples, internal control or feedback data relative to the battery charging process is transmitted for external reception via the same magnetic induction elements used in the charging process. While internally generated, such simple feedback signals are effectively powered by the charging process and therefor of little consequence to the normal operation of the implanted device.
In U.S. Patent Application Publication No. 2007/0167867 to Wolf for a System for Transcutaneous Monitoring of Intracranial Pressure, an implantable sensor module measures and communicates an intracranial pressure to an external module via, in one embodiment, a near infrared (NIR) beam that traverses biological tissue for the digital transmission of data, wherein the sensor module, rather than being battery-powered, is externally powered via inductive coupling with the exterior module. Alternatively, the sensing module is provided with pressure sensing circuits having a pressure-variable resonance, wherein an external circuit is configured to excite and detect a resonant frequency of the internal circuit(s) and thereby ascertain an intracranial pressure. Once again, while information is being relayed from the implanted device, the sensing module in these examples is effectively powered via external means.
Another example making use of optical communication means is provided in Active Microelectronic Neurosensor Arrays for Implantable Brain Communication Interfaces to Song et al. (IEEE Trans Neural Syst Rehabil Eng. 2009 August, 17(4), 339-345). In this example, the wireless transmission of implanted neurosensor array data is implemented via an integrated semiconductor diode laser, wherein the implanted device is powered via inductive or optical coupling.
An alternative approach relies rather on radio frequency (RF) transmissions, for example implemented via various frequency modulated (FM) transmission schemes or the like readily known in the art. Some examples applying this approach may be found in the following: A miniaturized Neuroprosthesis Suitable for Implantation into the Brain to Mojarradi et al. (IEEE Transactions on Neural Systems and Rehabilitation Engineering, Vol. 11, No. 1, March 2003); Wireless Multichannel Biopotential Recording Using an Integrated FM Telemetry Circuit to Mohseni (IEEE Transaction on Neural Systems and Rehabilitation Engineering, Vol. 13, No. 3, September 2005); A Single-Chip Signal Processing and Telemetry Engine for an Implantable 96-Channel Neural Data Acquisition System to Rizk et al. (J. Neural Eng. 4 (2007) 309-321); HermesC: RF Wireless Low-Power Neural Recording System for Freely Behaving Primates to Chestek et al. (Proceedings of the 2008 IEEE International Symposium on Circuits and Systems (ISCAS2008), Seattle, Wash. 2008, p. 1752-1755); International Application Publication No. WO2007/061654 to Kenergy, Inc.
Another such example is provided by US Patent Application No. 2010/0106041 to Ghovanloo et al. for Systems and Methods for Multichannel Wireless Implantable Neural Recording. In this example, an implantable system is provided wherein a neural signal from each of a number of data channels are converted to a pulse-width-modulated time-division-multiplexed signal that is ultimately transmitted via an RF transmitter (e.g. FM/FSK signal) for reception and reconstruction by an external device.
While the above introduce some prospects in the provision of wireless communications between implanted and externally disposed devices, such provisions are generally limited either in the complexity of the data being communicated (i.e. feedback/control data), by the complexity of the communication scheme (e.g. RF technologies) and associated drawbacks (power consumption, implanted circuit complexity, compliance with different wireless communication regulations, etc.). Furthermore, while optical communication schemes may be applicable in some circumstances, they may pose certain difficulties for certain applications, as will be readily appreciated by one of ordinary skill in the art.
Therefore, there remains a need for a wireless implantable data communication system, method and sensing device that overcomes some of the drawbacks of known technologies, or at least, provides the public with a useful alternative.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.